Amplifier.



G. W. PIGKARD.

AMPLIFIER. APPLICATION FILED we. 7, 1907. 1,027,755. v Patented May 28, 1912.

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4 specification of Letters Patent. Patented May 28,1912.

Application m ta August 7, 1907. Serial m. 387,389.

To all whomz't may concern r Be it known that I, GnnnNmAr'WHrrTmn Promo, a citizen of the United States of America, and a resident of the town of Amesbury, State ofvMassachusetts, have invented a certain new and useful. Amplifier, the principles of which are set forth in the following specification and accom anying drawing, which disclose the form 0 the invention which I now'consider to be the bestof the variqus forms in which those principles may be embodied.

This invention relates to at liquid amplifier for use as a'relay or as a repeater in any electrical circuits employing minute amounts of energy, and particularly inreceiving circuits of. installations for the communication of intelligence by. electromagnetic waves. The invention may also be used directly as a detector of wireless telegraphy oscillations.

An object of the invention is to obtain a reliable device which will make practicable the controlby feeble-received impulses of large amounts of auxiliary energy to permit the positive operation thereby of suitable indicating apparatus, and particularly, independently of the operation and electrical closure of metallic contacts by the feeble en:

ergy of received communications. Heretofore such devices have been hampered or limited, either by instability of op-' eration, or by narrow limits of control of the auxiliary source of energy, as the mechanical forces resulting from very feeble currents are insufficient for the positive opening and closing of conducting contacts. This invention consists of means which is stable in its operation and which permits wide limits of control ofauxiliary energy. In accordancel-herewith a circuit containing an auxiliary source of electromotive force iscontrolled by the variation of the resistance of a conducting liquid path or paths in the circuit, this variation {being effected by the short movement-through theliquid of a low-inertia member of thecircuit, the

movement of which is caused by the feeble I contact between solid conductors by the mechanical vforces resulting from feeble currents. By this invention such troubles are obviated, by the expedient of dispensing with any such contact-making arrangement.

connected to the battery B by the wire 5 on one side, and on the other side by either of the portions R or R of the conducting liquid L in the receptacle N. The terminals D and E are fixed int-he liquid L, and may be a few hundredths of an inch apart, the part F lying normally midway between them, so that R and R each possesses the same resistance.

The circuit includes a Wheatstone bridge, of which the fixed resistances R B constitute one arm, and, the variable resistances R R the'other. The circuit includes also the polarized relay or electromagnet P, hav- 7 ing a contact-controlling-arm or tongue -M.

The movement of the conducting part F to left or rig t from its midway position, will vary resistances R or R increasing one and decreasing the other, thus throwing the bridge out of balance and operating the relay P, throwing its contact arm or tongue in one or the other direction to close a circuit 3'or 4 of a local auxiliary source of electromotive force and operate any desired indicating mechanism.

The bridge circuit may -be adjusted so bridge relay P, and so give the desired signal.

The only opposition to the motion of the part F is the damping of the liquid, which is too slight to hinder efi'ectual working, but may be made suificient to insure uniformity of operation by acting as a governor.

The arm F may, among its various possible modes of use, be mounted on and moved by the suitably suspended oscillatable coil C, which maybe suchas is commonly used with the siphon recorder. The terminals 1 -1 by electromagnetic waves used to cmmu-q- 2 of coil C may be connected to the terminals of any telegraph or cable system, or 'to the circuit of a detector of oscillations produced nicate intelligence; or the part C may be the movable coil of an electro-dynamometer cei-ving circuit, without the use of any' other detector.

When used in telegraphy for recording purposes, the movement "of the coil C and arm A, and of tongue M, ,in two directions, to alternately close circuits 3 and 4, may be for dot and dash records; or when used with electromagnetic waves, only one 'movement of arm A maybe used, of short and long durations for dots and dashes, the tongue M of relay P being used to close a local indicating circuit, either '3 or 4, through a telephone or recording-indicating mechanism,

and a source of 'electromotive force therefor. When the parts C, A and F return to their' normal position midway between D and E, upon the cessation of a received impulse, the relay P will stop acting, its tongue M being returned to its inoperative position with respect to; the circuitsB and 4. The tongue M may have considerable inertia by weightand by return-spring, and any sultable means of eliminating contact-sticklng, because it is operated by the energy of a battery B, and not by the feeble energy received in coil C. s

7 Instead of being moved by the coil O,.the

'- arm F may bemade telephonically movable,

- resenting the complete T phragm.

' tacts at the parts as shown in Fig. 2, a ortion F of the arm F serv ng as the telep one armature, in cooperation with a suitable coil and core C the 0011 being supplied with current the effects of which it is desired" to amplify, such comprises a suitable electrical lndicat ng device and a divided circuit containlng an as those-used in connection with a wireless telegraph detector. In this case the device P M, 3, 4 ofFig. 1- iiiay' be a telephone re ceiver, as that shown in Fig. 2, the coil 0 thereof'belng in the circuit in place of the "0011 01; P, and the parts F, F of Fig, ;2, repsince there are no metallic conmoved by the coils'C or C, there can be no sticking of contacts which will interfere w th perfect independence of Obviously,

" the coil of all action except that due to received impulses. I 1

In the claims the specification of the conductors-as' projecting into the liquid, means telephone (liar v, v operated by t fi simply an operative conducting connection 7 therewith.

' I claim Y 1; Means for amplifying feeble electrical impulses, which comprises two variable resistance liquid conducting paths constituting one side of a Wheatstonebridge, and means operated by the feeble electrical impulses to vary said liquid resistances .and thereby unbalance the bridge.

, In an amplifier of feeble electrical impulses, the combination with a conducting liquid; of two conductors supported in pos r sition to include the liquid in circuit between them; a third conductor which is movable through the liquid between said conductors; a Wheatstone bridge including all said conductors and the included liquid; and means operated by the feeble impulses to movesaid third conductor through the liquid.

3. An amplifier, of feeble electrical impulses, which comprises aWheatstonebridge having a conducting liquid in one arm,

and including an electromagnetic circuit.

closer; and means operated by the feeble impulses to vary the resistance-distribution of said liquid in the bridge arm.

4. In an amplifier of'feeble electrical im pulses, the combination with. a Wheatstone bridge having fixed resistance in one side, and a normally-balanced variable liquid resistance in the other'side;'of.mea ns operated by the feeble impulses to unbalance said liquid resistance. K

TyIn an amplifier, the combination with an arm of a Whe'atstone bridge including a conductingl iquid; of a movable electrode in circuit with the bridge and said liquid; and means for moving said electrode in the liquid to unbalance the resistance thereof.

6; An electric" current amplifier, which auxiliary source of E. M. F., the two sides of'gaid circuit being normally balanced with 'respect to said indicating device; and two 

